"Rugby throws up plenty of challenges, and while I've thoroughly enjoyed my time in Wales, my next challenge is in Australia," said 43-year-old Johnson, who will return down under when his Wales contract expires in May.

"It has not been an easy decision for me to reach but, for once, I have had to put my family first.

"I've always been open and honest with the WRU, the Welsh players and the Welsh public on this issue and I would have loved to have stayed had it been possible.

Scott made it clear to us he would not be applying for the head coach role

WRU chief executive Steve Lewis

"Knuckles [Connolly] and [Australian Rugby Union boss] Gary Flowers have provided me with a great opportunity to return home and work with some of the world's best players.

"It's an understatement to say I'm looking forward to it, but I will leave Wales with some fond memories and also plenty of experience.

"I would love the opportunity to come back to Welsh rugby in some capacity in the near future as I could think of no better place to settle."

Johnson is widely credited as the brain behind Wales' all-action brand of rugby that helped them to the 2005 Grand Slam, but since taking over in difficult circumstances he has led them to two defeats and a draw against Italy.

Scott has been under enormous pressure over the last month or so

Australia coach John Connolly

WRU chief executive Steve Lewis was keen to pay tribute to Johnson's role with the national team.

"We would like to thank him for the important role he played both as a skills coach under Steve Hansen and Mike Ruddock and as the interim head coach in recent months," said Lewis.

"Scott made it clear to us he would not be applying for the head coach role and, as a result, any extension of his position within the Welsh coaching team would have been in the hands of whoever is appointed by the WRU.

"However, it is plain for all to see that the impact he has had on the international players he has worked with since coming to Wales in 2001 has had a hugely beneficial effect on them."